A new polymer that heals itself within seconds under light offers a future vision of cars, floors and other coated surfaces free of scratches, scuffs and dings.
“This is ingenious and transformative materials research,” said Andrew Lovinger, polymers program director at the National Science Foundation’s Division of Materials Research, which helped fund the effort.
“We came up with this idea to basically develop a coating, that if it was scratched, you could simply take out a light and heal the scratch,” Dr. Stuart Rowan explains in a video and simulation
about the research he is leading at Case Western Reserve University in Cleveland.
The ‘Eureka!’ Moment
The new material—known as “metallo-supramolecular polymers”—was an unexpected outgrowth of research that Rowan’s engineering team was pursuing. As a “quick experiment,” the team took a razor blade to the material in development, then put it under a UV light. Within 30 seconds, Rowan said, the scratch disappeared.
“That was the ‘Eureka!’ moment,” he said in the video
. “That was when [we thought] ‘Wow, we’ve got something really cool here.’”
The project also involves researchers at the Adolphe Merkle Institute of the University of Fribourg in Switzerland, led by Christoph Weder; and the Army Research Laboratory at Aberdeen Proving Ground in Maryland, led by Rick Beyer.
Images: Case Western Reserve University
|Under UV light, similar to that used by dentists to cure fillings, the scratch healed in less than 30 seconds.|
Their work, detailed in the April 21 issue of the journal Nature, shows how the polymer-based material becomes liquid and fills in the gaps of scrapes and scratches when exposed to ultraviolet light.
Polymers with a ‘Napoleon Complex’
Unlike conventional polymers, which consist of long, chain-like molecules with thousands of atoms, these materials are composed of smaller molecular chains, which are assembled into longer chains. The chains disassemble on exposure to light, then reassemble and solidify with the original properties restored when the light is turned off.
Using lamps such as those dentists use to cure fillings, the researchers repaired scratches in their polymers. Wherever they waved the light beam, the scratches filled up and disappeared. Moreover, repeated injuries did not seem to affect the material’s durability. Tests showed the materials could be repeatedly scratched and heal in the same location.
|The next step is to develop industrial coatings that harness the technology, says Dr. Stuart Rowan.|
“These polymers have a Napoleon Complex,” says Rowan, a professor of macromolecular engineering and science and director of Case Western’s Institute for Advanced Materials. “In reality they're pretty small but are designed to behave like they're big by taking advantage of specific weak molecular interactions.”
The scientists envision a wide variety of future applications and say that discussions with manufacturers are already underway to bring the concept to market.
Said Rowan: “One of our next steps is to use the concepts we have shown here to design a coating that would be more applicable in an industrial setting.”